Ah, Grishka, you're right! I didn't think of this kind of worms because the Spanish part of me calls them "gusanos" and for the French part of me "lombrices" are "lombrics" = earthworms and I was picturing God giving them earthworms to eat. Many countryside children challenge some others -usually younger or weaker kids- to eat an earthworm.

So the last line should be just:

"And to the ones who're naughty, He gives them worms."